Arena

In Arena, battles have predetermined length. They also require credits to start. The first time you clear a new arena, you get a significant credit bonus (it is stated on the arena page, but what it doesn't state is that the bonus will include all of your credit bonuses!). After you clear an arena once, the bonuses become much poorer, once a day they reset themselves to the cost of entering the arena (hence most people do arena's once a day). The entry cost also increase after an arena is cleared, which also resets each day.

Ending an arena is also guaranteed to net you a random item (with the usual tiny chance of getting an artifact and equipment).

This is how many monsters are in each rounds of area challenges.

Legend:

Round Title(#) = number of rounds

^ = number of boss monsters

! = number of Legendary monsters

First Blood(1): 1

Baby Steps(1): 2

Learning Curves(2): 1,2

Schooltastic(2): 2,3

Graduation(3): 2,2,3

From here on, difficulty setting has to be min. normal

A New Beginning(4): 2,2,2,4^

Test of Faith(5): 2,2,2,3,5^

Road Less Traveled(6): 2,2,2,3,3,5^

A Rolling Stone(7): 3,3,3,3,4,4,6^

Blazing Field(8): 3,3,3,3,4,5,5,7^

Fresh Meat(9): 2,2,2,2,3^,4^,4^,5^,6^^

Dark Skies(10): 3,3,3,3,4^,4^,5^,5^,6^,7^^

Growing Storm(12): 3,3,3,3,3,4^,4^,4^,5^,5^,6^,7^^

Apocalypse Soon(14): 3,3,3,3,3,3,4^,4^,4^,5^,5^,5^,6^,7^^

Power Flux(16): 3,3,4,4,4,5,5,6^,6^,6^6^,7^,7^,7^,7^,9^^

Killzone(18): 3,3,4,4,4,4,4,5,6^,6^,6^,6^^,6^^,6^^,6^^,6^^,6^^,7^^^

Endgame(20): 2,2,2,2,2,2,3^,3^,3^,3^,3^,3^,3^,4^^,4^^,5^^,5^^,5^^,7^^!

Only appear once Endgame has been conquered

Twisted Plots(25): 2,2,2,2,2,2,2,2,3^,3^,3^,3^,3^,3^,3^,3^,4^^,4^^,4^^,4^^,5^^,5^^,5^^,5^^,7^^^!